Both methods are used in color CRT monitors. Beam penetration method is used for random scan monitors. In beam penetration two layers of phosphor red and green are coated inside CRT screen, the display of color depend on how far electron excites outer red layer, then green layer. This method can produce four colors i.e red ,green, orange, yellow. This is less costly method as compared to shadow mask.

But it can produce less colors as compared to shadow mask. The quality of picture is also poor as compared to shadow mask. Shadow mask is used for raster scan systems. It can produce wide variety of colors .There is three phosphor color dots at each pixel position. One phosphor dot emit red light, another emit green light ,third emit blue light. Three guns one for each color are used. Three beams pass through holes in shadow mask, and a small color spot on screen is appeared. Shadow masks are used as display device for home computers, color tv set etc